Crippling of Klebsiella pneumoniae virulence by metformin, N-acetylcysteine and secnidazole.

INTRODUCTION: The emergence of multidrug-resistant Klebsiella pneumoniae in hospitals represents a serious threat to public health. Infections caused by Klebsiella pneumoniae are widespread in healthcare institutions, mainly pneumonia, bloodstream infections, and infections affecting neonates in intensive care units; so, it is necessary to combat this pathogen with new strategies. Targeting virulence factors necessary to induce host damage and disease is a new paradigm for antimicrobial therapy with several potential benefits that could lead to decreased resistance. BACKGROUND: The influence of metformin, N-acetylcysteine, and secnidazole on Klebsiella pneumoniae virulence factors production was tested. The production of Klebsiella pneumoniae virulence factors such as biofilm formation, urease, proteases, hemolysins, and tolerance to oxidative stress was evaluated phenotypically using sub-inhibitory concentration (1/8 MIC) of metformin, N-acetylcysteine, and secnidazole. For more confirmation, qRT-PCR was used to assess the relative expression level of rmpA, wcaG, fimH-1, mrkD, ureA, and khe genes regulating virulence factors production. RESULTS: Metformin, N-acetylcysteine, and secnidazole were all found to have a powerful inhibitory effect on the production of virulence factors phenotypically. Our results showed a significant reduction in the expression level of rmpA, wcaG, fimH-1, mrkD, ureA, and khe genes. Furthermore, the tested drugs were investigated in vivo to inform their ability to protect mice against Klebsiella pneumoniae pathogenesis. CONCLUSIONS: Metformin, N-acetylcysteine, and secnidazole inhibited the virulence of Klebsiella pneumoniae. Besides combating resistant Klebsiella pneumoniae, the tested drugs could also serve as an adjuvant to traditional antibiotics.

Attenuating the virulence of the resistant superbug Staphylococcus aureus bacteria isolated from neonatal sepsis by ascorbic acid, dexamethasone, and sodium bicarbonate.

BACKGROUND: Infections affecting neonates caused by Staphylococcus aureus are widespread in healthcare facilities; hence, novel strategies are needed to fight this pathogen. In this study, we aimed to investigate the effectiveness of the FDA-approved medications ascorbic acid, dexamethasone, and sodium bicarbonate to reduce the virulence of the resistant Staphylococcus aureus bacteria that causes neonatal sepsis and seek out suitable alternatives to the problem of multi-drug resistance. METHODS: Tested drugs were assessed phenotypically and genotypically for their effects on virulence factors and virulence-encoding genes in Staphylococcus aureus. Furthermore, drugs were tested in vivo for their ability to reduce Staphylococcus aureus pathogenesis. RESULTS: Sub-inhibitory concentrations (1/8 MIC) of ascorbic acid, dexamethasone, and sodium bicarbonate reduced the production of Staphylococcus aureus virulence factors, including biofilm formation, staphyloxanthin, proteases, and hemolysin production, as well as resistance to oxidative stress. At the molecular level, qRT-PCR was used to assess the relative expression levels of crtM, sigB, sarA, agrA, hla, fnbA, and icaA genes regulating virulence factors production and showed a significant reduction in the relative expression levels of all the tested genes. CONCLUSIONS: The current findings reveal that ascorbic acid, dexamethasone, and sodium bicarbonate have strong anti-virulence effects against Staphylococcus aureus. Thus, suggesting that they might be used as adjuvants to treat infections caused by Staphylococcus aureus in combination with conventional antimicrobials or as alternative therapies.

In a search for potential drug candidates for combating COVID-19: computational study revealed salvianolic acid B as a potential therapeutic targeting 3CLpro and spike proteins.

The global prevalence of COVID-19 disease and the overwhelming increase in death toll urge scientists to discover new effective drugs. Although the drug discovery process is a challenging and time-consuming, fortunately, the plant kingdom was found to have many active therapeutics possessing broad-spectrum antiviral activity including those candidates active against severe acute respiratory syndrome coronaviruses (SARS-CoV). Herein, nine traditional Chinese medicinal plant constituents from different origins (Glycyrrhizin 1, Lycorine 2, Puerarin 3, Daidzein 4, Daidzin 5, Salvianolic acid B 6, Dihydrotanshinone I 7, Tanshinone I 8, Tanshinone IIa 9) previously reported to exhibit antiviral activity against SARS-CoV were virtually screened in silico (molecular docking) as potential inhibitors of SARS-CoV-2 target proteins. The tested medicinal plant compounds were in silico screened for their activity against two key SARS-CoV-2 target proteins; 3CLpro, and Spike binding-domain proteins. Among the tested medicinal plant compounds, Salvianolic acid B 6 (Sal-B) showed promising binding affinities against the two specified SARS-CoV-2 target proteins compared to the reference standards used. Hence molecular dynamics simulations followed by calculating the free-binding energy were carried out for Sal-B providing information on its affinity, stability, and thermodynamic behavior within the two SARS-CoV-2 target proteins as well as key ligand-protein binding aspects. Besides, the quantum mechanical calculations showed that Sal-B can adopt different conformations due to the existence of various rotatable bonds. Therefore, the enhanced antiviral activity of Sal-B among other studied compounds can be also attributed to the structural flexibility of Sal-B. Our study gives an explanation of the structure activity relationship required for targeting SARS-CoV-2 3CLpro and Spike proteins and also facilitates the future design and synthesis of new potential drugs exhibiting better affinity and specificity. Besides, an ADME study was carried out on screened compounds and reference controls revealing their pharmacokinetics properties.Communicated by Ramaswamy H. Sarma.

Zinc oxide nanoparticles inhibits quorum sensing and virulence in Pseudomonas aeruginosa.

BACKGROUND: Quorum sensing inhibitionis an advanced strategy that aims to interfere with bacterial cell-to-cell communication systems (quorum sensing), which regulate virulence factors production in Pseudomonas aeruginosa, in order to overcome the globalcrisis of antimicrobial resistance. OBJECTIVES: Study the potential quorum sensing inhibitory effect of Zinc oxide (ZnO)nanoparticlesin Pseudomonas aeruginosa and the impact on production of virulence factors. METHODS: Quorum sensing inhibitory effect of ZnO was evaluated by assessing its ability to reducePseudomonas aeruginosa virulence factors production; rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, qRT-PCR was performed to determine ZnO inhibitory effect onQS-regulatory geneslasI, lasR, rhlI, rhlR, pqsA and pqsR that control virulence factors secretion. Moreover, mice survival test was conducted to investigate the influence of ZnO on Pseudomonas aeruginosa-induced mortality in vivo. RESULTS: ZnO revealed a statistically significant reduction in the production of QS-controlled virulence factors rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, ZnO exhibited a significant decrease in the relative expression of QS-regulatory geneslasI, lasR, rhlI, rhlR, pqsA and pqsR. Additionally, ZnO significantly reduced the pathogenesis of Pseudomonas aeruginosa in vivo. CONCLUSION: ZnO nanoparticles can be used as a quorum sensing inhibitor in Pseudomonas aeruginosa infections either as an adjuvant or alternative to conventional antimicrobials.